Late-Life Psychosis Mimics Schizophrenia

Late-Life Psychosis Mimics Schizophrenia

Article excerpt

EDINBURGH -- Age greater than 60 years is a major risk factor for onset of a nonorganic, nonaffective psychosis that's surprisingly common yet largely unappreciated outside the relatively small world of geriatric psychiatry.

"This late-life psychosis looks a bit like schizophrenia, but it isn't schizophrenia. It has risk factors and features that are similar to, and others that are different from, schizophrenia," Dr. Robert Howard observed at the congress.

Several decades ago, he and his coinvestigators studied the age at first psychiatric hospitalization for nonorganic, nonaffective psychosis in the United Kingdom and the Netherlands and demonstrated the existence of two peaks in incidence. The first occurs in individuals in their late teens and early 20s, the time of greatest risk for classic new-onset schizophrenia.

The second peak rises steeply after age 60 and summits in the 80s. The incidence of this late-life psychosis is greater in women than in men, just opposite the gender pattern for schizophrenia in younger people.

"In fact, if you're a woman, the most risky time in your life for developing a psychosis--and I'm not talking about the psychosis associated with dementia--is old age," according to Dr. Howard, professor of old-age psychiatry and psychopathology at the Institute of Psychiatry, King's College London.

He chaired an international consensus conference which, after much debate, chose the term "very late-onset schizophrenia-like psychosis" to describe this nonorganic psychosis with onset after age 60 (Am. J. Psychiatry 2000;157:172-8). It's an awkward term, Dr. Howard conceded, but after a full day of argument it was the only one the world's experts on schizophrenia could agree on.

"We used to call it late paraphrenia.' That never caught on beyond the U.K. Whenever I speak on this in the U.S., I have to explain that these patients don't have dementia," said Dr. Howard, also the dean of the Royal College of Psychiatrists. These late-life psychosis patients have all the classic symptoms of schizophrenia in the young, with one striking exception: no formal thought disorder.

"I must have personally sat down and spent time with 700-800 patients with late-life psychosis, and I've never seen one with a formal thought disorder. And they very rarely develop negative symptoms. I won't say never, but negative symptoms are extremely rare in this group," Dr. Howard continued.

Elderly patients with new-onset nonorganic, nonaffective psychosis also display several symptoms that just aren't found in younger schizophrenia patients. Roughly 80% of them have partition delusions: a belief that something that normally acts as a physical boundary--say, walls, floors, ceilings--no longer does so.

"These patients will tell you that they don't know how he does it, but the man next door is able to walk through the wall, paint all the ornaments in the china cupboard red, and then walk back out the same way. Or the lady upstairs has a special camera that allows her to see through the ceiling. These are absolutely characteristic of these patients," he said.

Another difference from schizophrenia in the young is that 20%-25% of these elderly patients experience vivid and complex Charles Bonnet syndrome-type visual hallucinations. Dr. William T. Carpenter Jr. said in an interview that the types of psychotic syndromes are numerous, and that hallucinations and delusions are not very discriminating between diagnostic categories. "It may be that many of the late-age-onset psychoses are not schizophrenia," said Dr. Carpenter, who is chair of the DSM-5 Psychotic Disorders Work Group. "Some [cases] may be brief psychosis; others might be disorder or induced by a medical condition or its treatment. In any case, schizophrenia is a very heterogeneous syndrome."

It is clear that patients with late-life psychosis perform very poorly on measures of executive function, motor skills, and verbal ability, according to Dr. …